Manufacture of shoes



Patented Mar. 31, 1942 MANUFACTURE OF SHOES Richard Almy, Lancaster Township, Lancaster County, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania No Drawing. Application June 12, 1941, Serial No. 397,739

33 Claims.

This application relates to the manufacture of shoes and is a continuation in part of my copending application, Serial No. 343,534, filed July 2, 1940. More particularly, this invention relates to a method of stiffening certain parts of shoes, for example, the toe and heel portions of the shoe upper, and to a shoe stiffener capable of use in substantially all types of shoes.

Shoe stiifeners heretofore used in the industry fall generally into two classes, first, thermoplastic stiffeners adapted to be rendered soft and pliable by the application of heat, and second, stiffeners adapted to be rendered soft and pliable by application of a suitable solvent. Thermoplastic stifi'eners are by far the cheaper of the two types of shoe stiffeners but possess numerous disadvantages which militate against their use. They are thermoplastic consequently when displayed in store windows and the like are susceptible to the heat of the sun, and fail to retain their shape and are subject to deformation. In some cases, the heat of the wearer's foot is .sufficient to cause deformation. They are generally brittle, hard, friable and inflexible, so that when exposed to deforming pressures they easily crack or break. In addition, they frequently stain the upper of the shoe in which they are inserted destroying the appearance of the shoe with consequent loss since such shoes cannot be sold. On the whole, they are so unsatisfactory that their use in the industry is due almost en-' tirely to their low cost.

The second type of shoe stiffeners comprises a base material impregnated with a stiffening compound such as a nitrocellulose solution, which is adapted to be softened or tempered by a suitable solvent to permit incorporation in shoes. Unfortunately. however, a tremendous fire hazard is present in the manufacture and use of such stiffeners, they are very expensive, and fre quently an insufficient amount of the stiffening compound is carried in the interstices of the base due to the difiiculties involved in satisfactorily impregnating the base material. This, of course, means that the stiffener is not satisfactory in use since it cannot perform its intended func tion. Moreover, it is difllcult or impossible to quickly temper such stiffeners since it requires considerable time for the solvent to penetrate into the body of the base. It will be observed this class of stiffeners leaves much to be desired in the manufacture of shoes.

A shoe stiffener to be satisfactory in use should be hard, resilient and flexible so that it will impart to a shoe a maximum degree of firmness and yet not be brittle, so that when subjected to a deforming pressure, it will resume its original shape upon removal of the deforming pressure. A stiffener should adhere to adjacent parts of a shoe to form a unitary structure but such adhesion should not be accompanied by staining. To fit in the rapid routine of shoe manufacture, stiffener blanks must be adapted to be rendered soft or tempered quickly, and when in such condition, they must be capable of lasting with little effort on the part of the operator. In, order that a shoe will keep its shape, the stiffening material in a blank must be resistant to temperatures ordinarily encountered in store windows and wear. The stiffening material of the blank must not attack the finish of the shoe and obviously may not be toxic to any degree which might be injurious to the wearer. The solvents used to condition the blank likewise may not be toxic to any degree which might be injurious to the wearer. Stiffeners, and the solvents used to temper them, should be noninfiammable to avoid fire hazards during the shoe manufacturing operation. A satisfactory shoe stiffener should possess the qualities above enumerated and still be capable of manufacture and sale at low cost so as to permit its universal application to all types of shoes. Even though a stifiener possess the above mentioned desirable qualities, if it be expensive in manufacture, it is of little or no commercial value.

The chief object of this invention is to provide a shoe stiffener embodying the desirable qualities above enumerated. An object of this invention is to provide a process of stiffening a shoe upper which is economical and readily and quickly carried out even by semi-skilled or unskilled labor. A further object is to provide a shoe embodying my improved stiffener. A still further object is to provide a method of making such stiffeners. A still further object is to provide a stiff, rigid, flexible, resilient shoe stifiener and a shoe containing the same, which can be economically produced in commercial manufacture.

The present invention relates to a shoe stiffener comprising a porous, absorbent base, which may be either paper, felt or fabric, and preferably is of cotton flannel, carrying or impregnated with a stiffening compound which includes a partially or incompletedcondensed, water-soluble, reactive aldehyde resin such as a partially or incompletely condensed, reactive urea "aldehyde resin stabilized in such stage. By partially or incompletely condensed urea-aldehyde resin, I mean a reactive urea-aldehyde resin in which the con-. densation reaction has been retarded or inhibited before it has proceeded to a stage in which the resin is infusible and insoluble in ordinary solvents such as water or alcohol. The term ureaaldehyde resin" is used herein to denote a ureaaldehyde resin, a thiourea-aldehyde resin, or similar urea-aldehyde derivatives. Preferably, the incompletely condensed urea resin is mixed with a resilient substance, such as rubber latex, either natural or concentrated, although rubber dispersions may be used in its place. Various synthetic rubber, such as chlorinated rubber, chloroprene, polymerized butadiene acrylic copolymers such as "Perbunan," synthetic rubbers of the olefin polysulflde type such as Thiokol, or polyisobutylenes such as Vistanex," may be substituted forthe rubber with satisfactory results.

After impregnating the absorbent base with the substantially homogeneous mixture of ureaaldehyde resin and rubber, the material is dried and furnished to the shoe manufacturer either in sheet form or severed in blanks of suitable size and shape for insertion in a shoe upper. It will be appreciated the urea-aldehyde resin carried by the stifiener blank at such time is water soluble to a substantial degree.

Immediately before the lasting operation, the blank is dipped or moistened in any desired manner with an aqueous solution of a material adapted to activate or accelerate the condensation reaction of the incompletely condensed urea-aldehyde resin. In other words, such solution serves as a catalyst to expedite the condensation of the resin to an infuslble, insoluble stage. The solution may be a dilute aqueous or alcoholic solution, either or both, of ammonium phosphate or similar acidic salts, phosphoric acid, tartaric acid, hydrochloric acid or the like. To accelerate the condensation reaction, it is essential that the hydrogen ion concentration of the urea-aldehyde resin be increased and any material which serves to increase the hydrogen ion concentration may be used. The reaction should not be accelerated too greatly since I have found in such case the resin precipitates in minute particles which is undesirable, rather than as a substantially continuous film. If desired, a suitable material may be incorporated in the activating solution to retard or inhibit the speed of the reaction to some extent and thus increase the time required for the resin to reach the infusible stage. This is desirable in some instances since stoppages, as at the end of a days operation, for example, may occur between the various manufacturing operations. I have found higher alcohols which evaporate slowly such as the cellosolves (methyl, isopropyl or butyl) the carbitols (methyl or butyl), and diacetone alcohol are suitable. The reactive resin is soluble in the activating solution so that the stiffener becomes soft and pliable and suitable for use in the lasting operation.

The blank is incorporated while moist in the shoe upper and the shoe is lasted while the blank is still in moist condition. The blank after lasting becomes hard, stiff, rigid, and flexible by evaporation of the activating solution and by substantially complete condensation of the ureaaldehyde resin which renders it infusible and insoluble. As pointed out above, care must be taken that the solvent for the resin is substantially evaporated from the blank before the resin proceeds to an infusible, insoluble stage else it precipitates in discrete particles instead of a continuous film and may render the stiffener unsatisfactory in use. The lasted stiffener may vary from a maximum hardness and minimum flexibility to a maximum flexibility and minimum hardness depending upon the proportions of the ingredients and the speed of the condensation reaction, which may be varied as desired to obtain the properties essential in the lasted stifiener.

The partially processed or incompletely condensed urea resin may be formed in the following manner, it being understood that the invention is not limited to the specific example, which is given merely for illustrative purposes. Ten pounds of crystalline urea and thirty pounds of formalin (37%) are charged into a reaction vessel equipped with a stirrer and the pH or hydrogen ion concentration is adjusted by the addition of a dilute solution of sodium hydroxide, potassium hydroxide or other suitable alkali at room temperature, about 70 to F.; the pH of the mixture is adjusted to about 5.5 to 7.0 and preferably to about 6.0 to 6.5. The temperature of the mixture is then raised with continued stirring to about to 180 F., and preferably between -160 F., and held at that temperature for approximately three hours in order to cause condensation. The pH of 5.5 to 7.0 must be maintained during the heating and until proper condensation is efiected. The mass tends to become acidic as heating proceeds and further additions of alkali may be found necessary in order to keep the pH adjusted to the desired range. At the end of the heating period suflicient dilute sodium hydroxide is added until the pH is raised to 9-11. The pH must be at least 9 and may be over 11. The temperature of the mass is then raised to the boiling point, around 190-200 F., and then further elevated to about 240 F., to remove water from the mass. Boiling the batch until its temperature reaches about 240 F. requires two to three hours and reduces the water content of the mass to approximately 20%. The

' pH during boiling becomes acidic and care should be taken that it does not go below 6.5. Addition of alkali may be made during boiling to maintain the pH between 6.5 and 7. The amount of water in the reacted product may be determined by weighing the amount of condensate produced during the reaction. If it be desired to remove still more water from the mass, it may be cooled below its general boiling point to about F. and vacuum applied to remove still more of the water. The resin so obtained is a rather viscous liquid which is substantially but not completely anhydrous and which slowly thickens over a period of weeks at room temperature but which may be quickly set by the addition at room temperature of an acidic accelerator as hereinafter set forth:

A satisfactory stiffening compound may be prepared as follows:

Parts by weight Urea-aldehyde resin solution 200 Rubber latex (40%) 250 Santomerse" 10 Soap solution (25%) 20 nation and drying, the stiffener blank contains the above ingredients in approximately the following proportions: Urea-aldehyde resin (incompletely condensed and water soluble) 160 parts by weight, rubber 100 parts by weight, "Santomerse 3 parts by weight, and soap 5 parts by weight.

As mentioned above, the urea-aldehyde resin used in the stiffening compound may be replaced by thiourea-aldehyde resins or various urea-aldehyde derivatives, melamine-aldehyde resins or phenol-aldehyde resins as will be more fully discussed hereinafter. Rubber latex is preferably used in the stiffening compound, either natural or concentrated, although rubber dispersions may be used in its place. If desired, various synthetic rubbers such as chloroprene, chlorinated rubber, polymerized butadiene acrylic copolymers (Perbunan), polyisobutylenes ("Vistanex"), or olefin polysulfides such as Thiokol, may be used with satisfactory results in place of the rubber latex. "Santomerse and the soap solution are wetting agents and are added to the so- .lution to ensure satisfactory impregnation of the porous, absorbent base; Santomerse is a commercial solution sold extensively as a wetting agent but is rather expensive so it is extended by an aqueous solution of hand soap. for example. It will be understood the wetting agent used in the stiffening compound may be composed entirely of either Santomerse" or hanl soap solution or both may be present in any desired proportions. If desired, any other of the commercial wetting agents such as Aquarex, may be substituted therefor. I have also found it desirable in some instances to add fillers to the above stiffening compound; such fillers may be diatomaceous earths such as Dicalite L, finely ground carpet waste or other suitable finely ground fibers, various clays such as bentonite, barium sulfate, whiting, or the like. Diatomaceous earths are particularly desirable as fillers since they serve to reduce the hygroscopicity of the stiffening compound while permitting the impregnated blank to remain sufficiently porous to be quickly moistened by the activating solution.

I have also found it desirable in some instances from a standpoint of economy to add still other stiffening materials tothe. stiffening compound above described. A satisfactory stiffening compound so modified is as follows:

Parts by weight Urea-aldehyde resin solution 200 Rubber latex (40%) 250 Soap solution -I 20 Starch (dry) 50-100 lized) 60 (40 parts solids) Santomerse "Darvan (dispersing agent) 2 Water 50 Fungicide (Dowicide) 0.2

maintain the diatomaceous earth suspended in the solution. It will be obvious any suitable dispersing agents may be used. Any fungicide such as "Dowicide" may be used to inhibit mold growth. The materials are mixed together to form a substantially homogeneous stiffening compound which is used to impregnate a porousabsorbent base. If desired to reduce the viscosity of the compound, additional water may be added, preferably at the time of impregnation of the base fabric.

The porous absorbent base of cotton flannel is impregnated or saturated with any of the above prepared stiffening compounds by passing a web of the material through a saturating tank, the excess saturant being removed by drawing the web through squeeze or pressure rolls or bars. The web is then dried by placing it for thirty minutes in a stove or oven heated to around 240 F. which deposits the stiffening compound in the interstices of the web and on the surface thereof by evaporation of the aqueous carrier. Shoe stiffener blanks of desired size and shape may then be cut or died from the web, or the web may be cut in sheets and so furnished to the shoe manufacturer. If desired, the blanks may be skived to form thin 'or tapered 'edges thereon. It will be appreciated at this stage the urea-aldehyde resin is still in an incompletely condensed stage and is water soluble and fusible.

If desired, vulcanizing ingredients may be added to the latex to vulcanize it during the drying operation or the rubber particles may exist in vulcanized form in the latex.

In assembling a shoe, immediately before the lasting operation, the stiffener blank is moistened, preferably by dipping, with an aqueous solution of a material adapted to activate or accelerate the condensation reaction of the incompletely condensed urea-aldehyde resin of the I stiffening compound. Preferably, the activating solution includes a retardant to inhibit or retard the speed of the reaction thus increasing the time during which such reaction occurs. the urea-aldehyde resin at this time is water soluble, the blank is softened and is rendered limp or pliable so that it can be lasted readily and quickly.

The accelerator solution may include any substance capable of increasing the hydrogen ion concentration of thesolution although relatively weak acidic materials such as ammonium phosphate are desirable and preferable. I may use a 10% by weight solution of phosphoric acid which I have found to be satisfactory since it does not hasten the condensation to so great an extent as to prevent lasting of the blank. Other acids, such as tartaric, lactic, acetic, hydrochloride and a large number of organic and inorganic acids or acidic salts, such as ammonium chloride, have a similar accelerating effect. It is desirable to use an acidic accelerator which produces a final pH in the resin of between 2 and 5 and preferably between 3 and 4. The inhibitor or retardant which increases the time during which the reaction occurs or, stated in other words, which decreases the speed 'of' the reaction, preferably, is diacetone alcohol although cellosolves such as methyl, isopropyl, and butyl, and carbitols such as methyl or butyl, may

"be used with satisfactory results. A satisfac- Since v soluble.

tory activating solution may comprise 65 parts by weight of water, 25 parts by weight of ammonium phosphate, and parts by weight of diacetone alcohol.

The stiifener blank, after remaining in the activating and tempering solution until it is suitably limp and pliable for lasting, is incorporated in the shoe upper, and is lasted while the blank is still in moist condition and the shoe is set aside to permit the blank to become hard and flexible. The blank, as pointed out above, hardens due to evaporation of the water and to the fact that condensation of the urea-aldehyde resin is carried to a substantially infusible, insoluble stage. If desired, the lasted stiffener may be heated in any suitable manner to accelerate condensation of the resin. Such heat application is not necessary but may be desirable in some instances where condensation of the resin in the lasted stiffener to an infusible insoluble stage is desired within an extremely short period of time.

It is essential that complete condensation of the resin does not occur before the evaporation of the water in the blank. If complete condensation occurs before the evaporation of water from the blank, the condensate precipitates in minute particles rather than as a film. To form a satisfactory stiffener, the urea-aldehyde resin should be present in film form. Accordingly, it is essential that the accelerator or activator for condensation be so chosen that complete condensation will not occur until the water has been substantially evaporated. By using a conditioning solution including an accelerator of properly adjusted strength or character and a retardant for the reaction the condensation reaction may be satisfactorily regulated.

The lasted shoe stiffener when dry is stiff, rigid, flexible, and resilient and is substantially unaffected by moisture. When subjected to a deforming pressure, it will resume its original shape upon removal of the deforming pressure. It is nonstaining and nontoxic and can be economically embodied in shoes. It is not subject to breaking or cracking by the forces usually encountered by shoes and reduces considerably the cost involved in shoe manufacture.

I have stated above phenol-aldehyde resins in a partially. or incompletely condensed stage may be used in place of the urea-aldehyde resin. The phenol-aldehyde resins may be prepared in the manner described above and likewise, preferably, are compounded with rubber to form the stiffening compound. A satisfactory stiffening compound including incompletely condensed phenolealdehyde resin is as follows:

Parts by weight Phenol-aldehyde resin solution 200 Rubber latex (40%) 250 Santomerse 10 Soap solution Such stiffening compound is used to impregnate a porous absorbent base, such as cotton flannel, and is dried. At such time, of course, the resin is incompletely condensed and is water In use, prior to the lasting operation, it is moistened, preferably by dipping, with an aqueous solution of accelerator for the condensation reaction which renders the blank limp and pliable. While still moist, it is placed in the shoe upper and lasted. Preferably, the accelerator or activator in this case is an aqueous solution of hydrochloric acid since the condensation generally is somewhat slower than is the case with urea-aldehyde resins. The lasted shoe stiffener is hardened and becomes rigid and flexible by evaporation of the water and by substantially complete condensation of the resin.

If desired, mixtures of incompletely condensed. reactive phenol-aldehyde and urea-aldehyde resins or resins formed by simultaneous condensation of urea and phenol with aldehydes such as formaldehyde, may be used as a stiffener compound. A satisfactory stiffening compound may be formulated as follows:

' Parts by weight Urea-aldehyde resin solution Phenol-aldehyde resin solution 100 Rubber latex (40%) 250 Santomerse" 10 Soap solution 20 It will be understood resins formed by simultaneous condensation of urea and phenol with aldehydes may be substituted in the above formula in place of the separately prepared resin solutions. Likewise, melamine-aldehyde resins in a partially or incompletely condensed stage may be used. Such resins may be prepared in the usual manner and, preferably, are mixed with rubber to form the stiffening compound. Fillers and additional stiffening materials as above described may likewise be incorporated with satisfactory results.

If desired, crystalline dimethylol urea may be dissolved in butanol in the presence of a catalyst such as hydrochloric acid and heated with ,continuous stirring to a temperature sufllcient to cause condensation and held at such temperature until a partially condensed resin is formed. The resin so formed may be stabilized in reactive or partially condensed condition by the addition of suitable alkali, such as sodium hydroxide. A porous, absorbent base is coated or impregnated with such stiffening compound and dried to form a stiffener blank. Immediately before the lasting operation, the stiffener blank may be moistened with an alcoholic solution of an activating or accelerating material to render the blank limp and pliable and to activate or accelerate the condensation reaction of the resin. The remaining steps of the process may be carried out as described above. The activating solution may be 10% by weight hydrochloric acid in ethyl alcohol. The lasted blank becomes hard, stiff and flexible by evaporation of the alcohol and by condensation of the resin to an infusible, insoluble stage.

The term "insoluble is used herein to characterize a resin which is not soluble in the usual solvents to any substantial extent; all resins are soluble to some minute degree dependent upon the conditions such as time and temperature under which the test takes place. Resins characterized herein as soluble are soluble to a substantial extent in water and/or alcohol while resins characterized as insoluble are only difficulty soluble to a minute degree.

While I have described and illustrated certain preferred embodiments of my invention, it will be understood my invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

I claim:

1. In the method of making shoes, the steps comprising moistening a shoe stiffener blank containing a reactive, water-soluble, aldehyde resin stabilized in incompletely condensed condition with an activating solution, incorporating the blank while in moist condition in a shoe upper, lasting the shoe while the blank is still in moist condition, and hardening the blank by further condensation of the resin.

2. In the method of making shoes, the steps comprising moistening a shoe stiffener blank containing reactive synthetic resin stabilized in incompletely condensed condition with a solution containing a substance adapted to accelerate the condensation reaction, such resin being chosen from a class consisting of urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melamine-aldehyde resin, and phenol-aldehyde resin, incorporating the blank while in moist condition in a shoe upper, and lasting the shoe while the blank is still in moist condition.

3. In the method of making shoes, the steps comprising moistening a shoe stiffener blank carrying a substantially homogeneous mixture of reactive urea-aldehyde resin stabilized in incompletely condensed condition and rubber with a solution adapted to accelerate the condensation reaction and to render the blank limp and pliable, incorporating the blank while pliable in a shoe upper, lasting the shoe while the blank is still pliable, heating the lasted blank to evaporate the solution, and. hardening the blank by evaporation of the solution and further condensation of the resin.

4. In the method of making shoes, the steps comprising moistening a substantially dry shoe stifiener blank carrying a substantially homogeneous mixture of reactive urea-aldehyde resin stabilized in incompletely condensed condition and rubber with an aqueous solution of a material adapted to accelerate the condensation reaction and to render the blank limp and pliable, incorporating the blank while limp and pliable in a shoe upper, lasting the shoe while the blank is still pliable, evaporating the water, and rendering the lasted blank substantially water resistant by condensation of the-resin to an infusible, water insoluble stage.

5. In the method of making shoes, the steps comprising moistening a substantially dry shoe stlfiener blank carrying a substantially homogeneous mixture of reactive urea-aldehyde resin stabilized in incompletely condensed condition and rubber with an aqueous solution capable of increasing the hydrogen ion concentration of the resin, incorporating the blank while in moist condition in a shoe upper, lasting the shoe while the blank is still in moist condition, and rendering the lasted blank substantially water resistant by condensation of the resin to an ini'usible, water insoluble stage.

6. In the method of making shoes, the steps comprising moistening a substantially dry shoe stiffener blank carrying a substantially homogeneous mixture of reactive urea-aldehyde resin stabilized in incompletely condensed condition and rubber with an aqueous solution of phosphoric acid to render the blank limp and pliable, incorporating the blank while limp and pliable in a shoe upper, lasting the shoe while the blank is still pliable and hardening the blank by evaporation of the water and further condensation of the resin.

7. In the method of treating a stifiener blank containing a dried, water-soluble, incompletely condensed aldehyde resin having a pH in the range of 6.5 to 7, the step of wetting said blank with a solution containing a solvent for said resin to render the blank readily deformable, and an agent which will change the pH of the resin to within the range of 2 to 5 at which substantially complete condensation of the resin will occur.

8. In the method of treating a stiffener blank containing a dried, water-soluble, incompletely condensed aldehyde resin having a pH in the range of 6.5 to 7, the steps of wetting said blank with a solution containing a solvent for said resin to render the blank readily deformable, and an agent which will change the pH of the resin to within the range of 2 to 5 at which substantially complete condensation of the resin will occur, and evaporating said solvent prior to complete condensation of said resin.

9. A lasted shoe including in its upper a shaped stifiener comprising a porous absorbent base impregnated with a substantially homogeneous mixture of synthetic resin and rubber, the synthetic resin being chosen from a group consisting of urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melamine-aldehyde resin, and phenol-aldehyde resin.

10. A lasted shoe including in its upper a shaped stiffener comprising a fibrous base impregnated with a substantially completely condensed urea-aldehyde resin and rubber.

11. A lasted shoe including a shaped stiffener comprising a porous absorbent fibrous base impregnated with a substantially homogeneous mixture of urea-aldehyde resin, rubber, and the dried residue of an aqueous solution of condensation accelerating material.

12. A lasted shoe including a shaped stiffener comprising a porous, absorbent fibrous base impregnated with a substantially homogeneous "mixture of urea-aldehyde resin, rubber, starch,

and clay.

13. A shoe stiffener comprising a porous absorbent base carrying substantially water insoluble urea-aldehyde resin, rubber'and the dried residue of an aqueous solution of phosphoric acid.

14. A shoe stiffener comprising a porous absorbent base impregnated with a substantially homogeneous mixture of water insoluble ureagldehyde resin, rubber, starch and a mineral ller.

15. A shoe stiffener blank comprising a fibrous base carrying reactive synthetic resin stabilized in partially condensed condition, such resin being chosen from a class consisting of urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melamine-aldehyde resin, and phenol-aldehyde resin.

16. A shoe stiffener blank comprising a porous absorbent b'ase impregnated with a mixture of reactive synthetic resin stabilized in partially condensed condition and rubber, said resin being chosen from a class'consisting of urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melamine-aldehyde resin and phenolaldehyde resin.

17. A lasted shoe stiffener comprising a base carrying substantially water insoluble synthetic resin chosen from a class consisting of ureaaldehyde resin, thiourea-aldehyde resin, ureaaldehyde derivatives, melamine-aldehyde resin, and phenol-aldehyde resin, the pH of the resin falling within the range of 2 to 5.

18. A lasted shoe stiffener according to claim 17 in which the pH of the resin falls within the range of 3 to 4.

19. A lasted shoe stiffener comprising a porous absorbent base impregnated with ahomogeneous mixture of substantially water insoluble ureaaldehyde resin and rubber, the pH of the resin falling within the range of 2 to 5.

20. A shoe stiflener blank according to claim in which the pH of the resin falls within the range of 6.5 to '7.

21. In the method of making a rigid, flexible, shoe stiffener blank, the steps comprising impregnating a porous absorbent base with a homogeneous mixture of water soluble urea-aldehyde resin stabilized in an incompletely condensed condition, drying the impregnated base, moistening the impregnated blank with a solution of by a material adapted to accelerate the condensation reaction, and hardening the blank by evaporation of the solution and further condensation of the resin.

22. In the method of making a rigid, flexible,

resilient shoe stiflener blank the steps comprising impregnating a porous absorbent base with a homogeneous mixture of water-soluble synthetic resin and rubber, said resin being chosen from a class consisting of reactive urea-aldehyde resin, reactive thiourea-aldehyde resin,-reactive ureaaldehyde derivatives, melamine-aldehyde resin, and reactive phenol-aldehyde resin, stabilized in incompletely condensed condition, drying the impregnated base, moistening .the impregnated blank with an aqueous solution of a material adapted to accelerate the condensation reaction, and hardening the blank by evaporation of water and condensation of the resin.

23. In the method of making a hard, tough, flexible fabric, the steps comprising impregnating a porous absorbent base with 'a homogeneous mixture of urea-aldehyde resin stabilized in an incompletely condensed condition and rubber, drying the impregnated base, and. moistening the impregnated base with an aqueous solution of a material adapted to accelerate the condensation reaction.

24. In the method of making shoes, the steps comprising moistening a shoe stifiener blank carrying a homogeneous mixture of reactive dimethylol urea resin stabilized in incompletely condensed condition with an alcoholic solution adapted to accelerate the condensation reaction, incorporating the blank while in moist condition in a shoe upper, lasting the shoe while the blank is still in moist condition, and hardening the blank by evaporation of the alcohol and further condensation of the resin.

25. A shoe stifiener comprising a porous. absorbent, fibrous base impregnated with a reactive, water-soluble, aldehyde resin.

26. A shoe stiffener comprising a fibrous base carrying a synthetic resin chosen from the class consisting of urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melaminealdehyde resin, and phenol-aldehyde resin, and rubber.

27. A shoe stiffener comprising a fibrous base carrying a reactive, water-soluble, aldehyde resin and diatomaceous earth.

28. A'shoe stiffener comprising a porous, absorbent, fibrous base impregnated with a mixture of synthetic resin, rubber and diatomaceous earth, said resin being chosen from a class consisting of urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melamine-alde resin, and phenol-aldehyde resin.

shoe stifiener blank comprising a fibrous b3 V a rrying diatomaceous earth and a reactive synthetic resin stabilized in partially condensed condition, said resin being chosen from a class consisting of urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melaminealdehyde resin, and phenol-aldehyde resin.

30. A shoe stiffener blank comprising a porous, absorbent base carrying a mixture of reactive synthetic resin stabilized in partially condensed condition, rubber and diatomaceous earth, said resin being chosen from a class consisting of urea-aldehyde resin, thiourea-aidehyde resin, urea-aldehyde derivatives, melamine-aldehyde resin, and phenol-aldehyde resin.

31. A shoe stiffener blank comprising a fibrous base carrying a synthetic resin chosen from the class consisting of reactive, water-soluble aldehyde resin, urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melaminealdehyde resin, and phenol-aldehyde resin.

32. In the method of making shoes, the steps comprising moistening a shoe stiffener blank containing reactive synthetic resin stabilized in incompletely condensed condition with a solution containing a substance adapted to accelerate the condensation reaction and a material adapted to retard the accelerated reaction. such resin being chosen from a class consisting of urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melamine-aldehyde resin, and phenol aldehyde resin. incorporating the blank while in moist condition in a shoe upper, and lasting the shoe while the blank is still in moist condition.

33. In the method of making shoes, the steps comprising moistening a shoe stiffener blank containing reactive synthetic resin stabilized in incompletely condensed condition with a solution containing ammonium phosphate and diacetone alcohol, such resin being chosen from a class consisting of urea-aldehyde resin, thiourea-aldehyde resin, urea-aldehyde derivatives, melaminealdehyde resin, and phenol-aldehyde resin, incorporating the blank while in moist condition in a shoe upper, and lasting the shoe while the blank is still in moist condition.

RICHARD ALMY.

DISCLAIMER 2,277,941.Richa1'd Almy, Lancaster Township, Lancaster County, Pa. MANU- FACTUBE 0F Snons. Patent dated Mar. 31, 1942. Disclaimer filed Aug.

26, 1946, by the assignee, Armstrong Cork Company.

Hereb disclaims the subject matter of claims 25 and 31; from claims 1, 2, 7, 8,

22, 32, and 33 the use of phenol aldehyde resin; from the scope of claims 9, 15, 16, 17, 18, 20, 26, 27, 28, 29, and 30 phenol aldehyde resin; from the specification of said Letters Patent, page 3, column 1, lines 11 and 12 the words "or phenol aldehyde resins; the descriptive matter commencing at page 4, column 1, line 48 and extending through page 4, column 2, line 29.

'[Qflic'ial Gazette October 1, 1.946.] 

